Study of Reflection-Lass-Based Material Identification from Common Building Surfaces

Abstract

Perceiving and recognizing material properties of surfaces and objects are fundamental aspects of new and emerging use cases such as robotic perception, virtual reality (VR) applications, digital twins, and creating a 3D digital map of an environment. In this paper, we present results from our simulation-based study of reflection-loss-based material identification from eight common building materials. The study focuses on 2.6 GHz, 28 GHz, and 60 GHz radio carrier frequencies. Analysis of simulation results indicates that a combination of incident angle and reflection loss can be used to properly identify the common building materials. We, therefore, propose a novel joint communication and sensing method for material recognition using reflection loss of the radio signal by the scatterers around the propagation path in a wireless communication network. Compared to existing material identification methods, the proposed reflection-loss-based method is capable of identifying materials from a significant distance without requiring any contact with the object and without requiring dedicated sensors from the infrastructure point of view.

Joint Scatterer Localization and Material Identification Using Radio Access Technology

“…By looking up Table III, a row with ΣRL=22.24 dB is found. From the information contained in this row, we can conclude that trajectory A is the true trajectory, RP1 locates at (8,10,8) and the first scatterer is made of wood, RP2 locates at (10, 7.5, 7.5) and the second scatterer is made of glass. The information of the two RPs can be used to represent two points in 3D space with 4-dimensional information including Cartesian coordinate (x, y, z) and material information.…”

“…From Fig. 4(a), for scatterers made of specific material, RL and incident angle are negatively correlated, large incident angle induces small RL [8].…”

“…For single-bounce reflection, a radio ray transmitted by the TX strikes the vertical wall with an incident angle θ i as shown in Fig. 3(a) [8], θ i is swept from 0°to 80°by changing the position of the RX. d t and d r are the path lengths between the RP and the TX/RX, respectively.…”

“…By the simulation steps proposed in [8], RL of single-and double-bounce reflection can be obtained. The received power at the RX side, which is attenuated by free space propagation and reflection at a certain incident angle, is measured in the first step.…”

“…The process of scatterer localization can be simplified by making single-bounce-assumption as workaround, but it cannot meet the extreme reliability requirements of some critical use cases, e.g., AD. In this article, we extend the capability of the method proposed in[8] from material identification only to both material identification and scatterer localization simultaneously. The extension is based on findings from RL simulations and theoretical analysis: (1) most of the ΣRLs induced by different sequences-of-material are significantly different; (2) RL is dependent on material of scatterer, radio frequency, and incident angle only; (3) ΣRLs induced by multiple scatterers is independent of scatterers' sequence-of-material.…”